19.1: Marine Community Zones
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Our discussion of the various communities that exist in the ocean will be separated according to 4 ocean zones. Of course, there is much community diversity than defined in this way, but this is a good starting point.
1) The intertidal zone, which is also called the littoral zone, is the section of the ocean on the shore that transitions between being submerged and emerged according to the tide. It begins at the high tide line and ends at the low tide line. This zone is the most extreme and also the most influenced from processes on land.
2) The subtidal zone, also referred to as the sublittoral zone, begins at the low tide line and continues over the continental shelf, usually to a depth of about 200 meters. Although this zone is nearly always submerged, the uppermost portion may occasionally be exposed during extreme low tide events. Because it is close to shore, this zone experiences changes attributed to processes on land.
3) The oceanic zone exists outside of the continental shelf, where the water depth exceeds 200 meters. Benthic communities in this area do not include photosynthetic organisms. The only photosynthetic organisms in this zone are plankton. Many nekton in this zone migrate between deeper and shallower waters.
4) The deep sea is the zone beginning at about 1000 meters depth. Here, there is no light and photosynthetic organisms are not present. Primary producers in this community rely on chemosynthesis, or the production of organic matter using inorganic compounds as the source of energy.